/* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.activiti.engine.impl.cmd;

import org.activiti.engine.impl.Page;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandContext;
import org.activiti.engine.impl.jobexecutor.AcquiredJobs;
import org.activiti.engine.impl.jobexecutor.JobExecutor;
import org.activiti.engine.impl.persistence.entity.JobEntity;
import org.activiti.engine.impl.persistence.entity.MessageEntity;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;


/**
 * @author Nick Burch
 * @author Daniel Meyer
 */
public class AcquireJobsCmd implements Command<AcquiredJobs> {

    private final JobExecutor jobExecutor;

    public AcquireJobsCmd(JobExecutor jobExecutor) {
        this.jobExecutor = jobExecutor;
    }

    public AcquiredJobs execute(CommandContext commandContext) {

        String lockOwner = jobExecutor.getLockOwner();
        int lockTimeInMillis = jobExecutor.getLockTimeInMillis();
        int maxNonExclusiveJobsPerAcquisition = jobExecutor.getMaxJobsPerAcquisition();

        AcquiredJobs acquiredJobs = new AcquiredJobs();
        List<JobEntity> jobs = commandContext
                .getJobEntityManager()
                .findNextJobsToExecute(new Page(0, maxNonExclusiveJobsPerAcquisition));

        for (JobEntity job : jobs) {
            List<String> jobIds = new ArrayList<String>();
            if (job != null && !acquiredJobs.contains(job.getId())) {
                if (job instanceof MessageEntity && job.isExclusive() && job.getProcessInstanceId() != null) {
                    // wait to get exclusive jobs within 100ms
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                    }

                    // acquire all exclusive jobs in the same process instance
                    // (includes the current job)
                    List<JobEntity> exclusiveJobs = commandContext.getJobEntityManager()
                            .findExclusiveJobsToExecute(job.getProcessInstanceId());
                    for (JobEntity exclusiveJob : exclusiveJobs) {
                        if (exclusiveJob != null) {
                            lockJob(commandContext, exclusiveJob, lockOwner, lockTimeInMillis);
                            jobIds.add(exclusiveJob.getId());
                        }
                    }

                } else {
                    lockJob(commandContext, job, lockOwner, lockTimeInMillis);
                    jobIds.add(job.getId());
                }

            }

            acquiredJobs.addJobIdBatch(jobIds);
        }

        return acquiredJobs;
    }

    protected void lockJob(CommandContext commandContext, JobEntity job, String lockOwner, int lockTimeInMillis) {
        job.setLockOwner(lockOwner);
        GregorianCalendar gregorianCalendar = new GregorianCalendar();
        gregorianCalendar.setTime(commandContext.getProcessEngineConfiguration().getClock().getCurrentTime());
        gregorianCalendar.add(Calendar.MILLISECOND, lockTimeInMillis);
        job.setLockExpirationTime(gregorianCalendar.getTime());
    }
}